Placebos - so how do they work?

Notes from "Placebo. The Belief Effect" Dylan Evans. Harper Collins Publishers, London. 2003.

While there is no scientific consensus on what actually causes the placebo effect, it is accepted that it begins with some neural response. Placebo effects are associated with a local release of endorphins in the body but its not clear how or where in the brain this release is triggered.
Evans proposes that the secret ingredient in the placebo response is belief and from the research I've done this seems to be a good explanation - one that is suitably vague and mysterious but believable and something we can all relate to. We take our beliefs very seriously.